Sample handling apparatus are used for cleanup and enrichment of chemical samples prior to chemical analysis. Typical operating procedures of such apparatus includes eluting a column packed with a sorbent using a solvent to wet the sorbent bed, loading a sample to the column, eluting the column again with a solvent to remove the interfering components from the sample, and then washing down the target component(s) in the sample from the column using a solvent and collecting the target component(s) fraction for further analysis. In conventional sample handling apparatus, valves are switched to divert solvents and sample fluids.
There are two general types of sample handling apparatus: single channel apparatus that process samples sequentially and multi-channel apparatus for parallel processing of multiple samples. Multi-channel apparatus offer faster sample throughput but involves more valves and more complicated tubing connections and control, resulting in higher cost.
Valves commonly used in conventional sample handling apparatus are solenoid driven valves (e.g., solenoid flow selection valves and isolation valve manufactured by Bio-Chem Fluidics, Boonton, N.J., USA) and rotary valves (e.g., multi-position valves manufactured by VICI Co., Houston, Tex., USA). A rotary valve comprises a stator with connection ports and a rotor with channels. Fluid can be diverted to a targeted port by rotating the rotor relative to the stator.
Examples of conventional multi-channel sample handling apparatus may be found in: 1) U.S. Pat No. 5,660,792 (Toshio Koike et al.); 2) AutoTrace SPE instrument brochure by Dionex Corporation (LPN2161, 02/09); 3) Automated liquid handling product guide by Gilson, Inc. (LT303041-11, page 40). Conventional designs such as these require at least one conventional valve for each channel.
Improved and cost-effective apparatus and methods for multi-channel sample handling are desirable.